Commit ac4119c0 authored by Jan Kiszka's avatar Jan Kiszka Committed by Aurelien Jarno
Browse files

chardev: Use timer instead of bottom-half to postpone open event 



As the block layer may decide to flush bottom-halfs while the machine is
still initializing (e.g. to read geometry data from the disk), our
postponed open event may be processed before the last frontend
registered with a muxed chardev.

Until the semantics of BHs have been clarified, use an expired timer to
achieve the same effect (suggested by Paolo Bonzini). This requires to
perform the alarm timer initialization earlier as otherwise timer
subsystem can be used before being ready.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
parent 40e3acc1

qemu-char.c

+7 −6
Original line number Diff line number Diff line
@@ -123,19 +123,20 @@ void qemu_chr_be_event(CharDriverState *s, int event) 
    s->chr_event(s->handler_opaque, event);

}



static void qemu_chr_generic_open_bh(void *opaque)

static void qemu_chr_fire_open_event(void *opaque)

{

    CharDriverState *s = opaque;

    qemu_chr_be_event(s, CHR_EVENT_OPENED);

    qemu_bh_delete(s->bh);

    s->bh = NULL;

    qemu_free_timer(s->open_timer);

    s->open_timer = NULL;

}



void qemu_chr_generic_open(CharDriverState *s)

{

    if (s->bh == NULL) {

	s->bh = qemu_bh_new(qemu_chr_generic_open_bh, s);

	qemu_bh_schedule(s->bh);

    if (s->open_timer == NULL) {

        s->open_timer = qemu_new_timer_ms(vm_clock,

                                          qemu_chr_fire_open_event, s);

        qemu_mod_timer(s->open_timer, qemu_get_clock_ms(vm_clock) - 1);

    }

}

qemu-char.h

+1 −1
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ struct CharDriverState { 
    void (*chr_guest_open)(struct CharDriverState *chr);

    void (*chr_guest_close)(struct CharDriverState *chr);

    void *opaque;

    QEMUBH *bh;

    QEMUTimer *open_timer;

    char *label;

    char *filename;

    int opened;

vl.c

+5 −5
Original line number Diff line number Diff line
@@ -3551,6 +3551,11 @@ int main(int argc, char **argv, char **envp) 
            add_device_config(DEV_VIRTCON, "vc:80Cx24C");

    }



    if (init_timer_alarm() < 0) {

        fprintf(stderr, "could not initialize alarm timer\n");

        exit(1);

    }



    socket_init();



    if (qemu_opts_foreach(qemu_find_opts("chardev"), chardev_init_func, NULL, 1) != 0)
@@ -3618,11 +3623,6 @@ int main(int argc, char **argv, char **envp) 


    os_set_line_buffering();



    if (init_timer_alarm() < 0) {

        fprintf(stderr, "could not initialize alarm timer\n");

        exit(1);

    }



#ifdef CONFIG_SPICE

    /* spice needs the timers to be initialized by this point */

    qemu_spice_init();